Incinerators

ABSTRACT

In a method of disposing of town refuse, the refuse is burnt whilst supported in an incinerator by a fluidized bed of refractory granular material and the bed is separated from an outlet of the incinerator container by a mass of refractory granular material which is periodically fluidized to allow the noncombustible content of the refuse to pass therethrough and be removed from the incinerator through the outlet. The mass of refractory granular material may form an extension of the bed which supports the refuse whilst it is burnt with the mass of granular material positioned between the part of the bed which supports the refuse and an outlet from the incinerator container.

References Cited UNITED STATES PATENTS United States Patent [72]Inventor Duncan Ronald Muirhead Narrow Lane, near Ferrby, England L. m eGST 7008 666 999 lll 2.18 l 0057 965 54,6, 217 01.9 3,4,3 333 .M .m L nm P m m l& 97 s 69n w1 w 9 9 nyym SWWR o. e N m e ,Wd ma@ P mm AFPA11:1] |253 224-/ r..[[[

Primary Examiner--Kenneth W. Sprague Kingston-upon-Hull, Yorkshire,England rNcrNEruiroRs This invention relates to a method of disposing oftown refuse by burning it in an incinerator and to incinerators suitablefor burning town refuse.

Until recently town refuse has been disposed of mainly by tipping intoworked-out quarries and mineshafts. As the number of sites suitable fortipping has gradually diminished and the quantity of refuse to bedisposed of has increased, the disposal of town refuse has become anincreasingly important problem to Local Authorities. The calorific valueof town refuse has however increased due mainly to an increase in theuse of disposable combustible materials for packaging purposes and anumber of proposals have been put forward for burning the refuse inincinerators. Conventional incinerators usually have some form oftravelling grate which supports the refuse and keeps it moving in theincinerator so that the combustible material can be completely burnt.Town refuse contains some noncombustible material and unless care istaken, this noncombustible material can quickly build up and clog thetravelling grate and also prevent an adequate air supply from reachingthe combustible material from beneath the grate.

According to the first aspect of the present invention in a method ofdisposing of town refuse, the refuse is deposited into an incineratorand the combustible content of the refuse is burnt whilst supported by afluidized bed of refractory granular material, and a mass of refractorygranular material separating said fluidized bed from an outlet of thecontainer is periodically fluidized to allow the noncombustible contentof the refuse to pass therethrough and be removed from said incineratorthrough said outlet.

The refractory granular material is conveniently fluidized by passingair therethrough.

When the mass of granular material is fluidized the noncombustiblecontent of the refuse is flushed out through the outlet by the flow ofsaid granular material therethrough. The mass of refractory granularmaterial in the bed then has to be restored to its original mass byadding granular material into the incinerator.

According to a second aspect of the present invention an incinerator forburning town refuse comprises an elongate container arranged with itslongitudinal axis substantially horizontal, said container defining afirst opening at one end thereof through which town refuse isintroducible into the container and defining a second opening at theother end thereof, a bed of granular refractory material in thecontainer extending between said ends with the surface of the bedpositioned below the first opening and above the second opening, meansfor passing a gaseous medium through a part of said bed extending fromthe end of the container adjacent to the first opening along the greaterpart of the length of the container to fluidize that part of the bed,and separate means for passing a gaseous medium through the remainingpart of the bed to fluidize that part of the bed.

Since there are no moving parts in the incinerator which correspond tothe travelling grate in a conventional incinerator, the noncombustiblecontent of the refuse cannot clog the moving parts and when thenoncombustible content of the refuse has built up in the incinerator themass of refractory granular material is fluidized to flush out thenoncombustible content from the container.

When the incinerator is in use, heat developed from the y burning refusemay be used to dry and burn slurries, for examl ple of sewage sludge,injected into the incinerator. Alternatively, or in addition, some ofthe heat developed in the incinerator may be absorbed by waste heatrecovery equipment such as a boiler or heat exchanger.

The town refuse is deposited onto the bed the greater part of the lengthof which is fluidized and the combustible material in the refuse eitherforms part of and burns in the fluidized bed or floats on the surfaceofthe bed while it burns. lf the combustible material burns whileforming part of the bed, the `bed must be fluidized by an oxidizinggaseous medium such as air. Further air or oxygen may be provided abovethe surface of the bed. lf the combustible material is burnt while itfloats on the surface of the bed, the bed is fluidized by a gaseousmedium or steam and a further supply of oxidizing gaseous medium mayhave to be provided above the surface of the bed. Any part of the refusewhich is not readily combustible eventually sinks through the bed anddue to the action of the bed moves towards the end of the bed adjacentthe nonfluidized mass of refractory granular material. This nonfluidizedmass prevents the granular material which is fluidized from leaving thecontainer through the outlet thereof. When it is desired to remove thenoncombustible content of the refuse from the incinerator, the part ofthe `bed adjacent the outlet from the container is fluidized allowingthe granular material forming at least that part of the bed to flow outthrough the outlet from the container bringing much of thenoncombustible material with it.

After the noncombustible part of the refuse has been flushed out of thecontainer it is necessary to add more granular material to the bed torestore it to its original depth and if desired the granular materialand the noncombustible content of the refuse may pass onto a screw whenit leaves the container so that the granular material passes through thescreen and is collected and returned to the container at the end thereofto which the town refuse is added.

ln order that the invention may be more readily understood it will nowbe described, by way of example only, with reference to the accompanyingdrawing in which:

The FIGURE is a sectional side elevation of an incinerator in accordancewith one embodiment of the invention.

An incinerator for burning town refuse comprises an elongate container3l arranged with its longitudinal axis substantially horizontal andhaving a lining 32 of solid refractory material. Alternatively the wallscan be constructed of forcecooled material. The base 33 of the containeris apertured and below the base there are two hollow boxes k34 and 35together extending the length of the container with the box 34 extendingfor the greater part of the length. The base 33 forms one wall of eachbox. At one end of the container there is an opening 36 through whichtown refuse is introduced into the incinerator and if desired the refusemay be shredded in a shredder 37 prior to being introduced into thecontainer. A second opening 38 at the other end of the container ispositioned adjacent the base thereof. The roof 39 of the container isinclined to the base so that the height of the container is a minimum atthe end adjacent the opening 38 and the roof leads into a smoke stack 40which may include a gas-cleaning system (not shown). A bed 4l ofgranular refractory material, such as sand, pulverized ash or alumina issupported on the base of the container and extends along the lengththereof. The surface of the bed is below the level of the opening 36 andabove the level of the opening 38. The part of the bed located above thebox 34 is fluidized by passing a gaseous medium such as air into thecontainer through theapertures in the base 33 from the box 34. Thegaseous medium is supplied to the box through a pipe 42 and iscontrolled by a valve 43 lfitted in the pipe. Similarly the part of thebed located above the air box 35 is fluidized by a gaseous medium suchas air or steam passed into the bed from the box 35 through theapertures in the base 33. The gaseous medium is supplied to the box 35through a pipe 44 and is controlled by a valve 45.

To start the incinerator, town refuse is supplied to the containerthrough the opening 36 and is supported on lthe surface of the bed ofgranular refractory material. A suitable fuel is introduced into theincinerator with the first load of refuse in order to ignite the refuseand once the granular refractory material is up to working temperaturethe combustible material in the refuse will ignite spontaneously as itfalls onto the bed and the supply of fuel to the incinerator can bestopped. A regulatable supply of air to the incinerator to assistcombustion enters the incinerator through a plurality of nozzles some ofwhich are indicated by reference numeral 46. 'The part of the bed abovethe box 34 is fluidized and the combustible content of the refuse isburnt in the fluidized bed or floats on the surface of the bed while itburns. lf the fluidizng gas is oxidizing, little or no air may besupplied through the nozzles 46. The fiuidized part of the bed is in themain prevented from leaving the container through the outlet 38 by thepart of the bed above the box 35 which is not fluidized and this part ofthe bed forms a dam which prevents the mass of fluidized material fromflowing out of the container. The noncombustible content of the townrefuse, will sink through the fiuidized bed and collect on the base 33of the container. The action of the gaseous medium supplied to the bedthrough the box 34 causes the noncombustible refuse to pass along thecontainer until it reaches the nonfiuidized part of the bed above thebox 35.

Periodically it is necessary to remove the noncombustible part of therefuse and to this end the part of the bed which forms the dam is thenfiuidized and a large part of the granular material flows out of theoutlet 38 flushing out the noncombustible content of the refuse with it.The gaseous medium supplied to the box 35 is then cut off and the partof the bcd above the box 35 is then rendered nonfluidized and forms adam which prevents further granular material from leaving the container.

The granular material and the noncombustible content of the refuseleaving the container through the opening 38 falls onto a screen 47which permits the granular material to pass therethrough while retainingthe noncombustible material. lt is necessary to keep the surface of thebed in the container at a substantially constant level above the base 33and to this end it is necessary to introduce granular refractorymaterial into the container through the opening 36 from time to time.When the screen 47 is employed the granular material pass therethroughcan be collected and returned into the container through the opening 36.

Sewage sludge can be sprayed into the incinerator through a plurality ofnozzles positioned above the surface of the fiuidized bed. Such nozzlesare indicated by reference numeral 48. The heat from the burning townrefuse in the incinerator dries out the sludge and the sludge is burntin the incinerator.

l claim:

l. An incinerator for burning town refuse comprising an elongatecontainer arranged with its longitudinal axis substantially horizontal,said container defining a first opening at one end thereof through whichtown refuse is introducible into the container and defining a secondopening at the other end thereof, a bed of granular refractory materialin the container extending between said ends with the surface of the bedpositioned below the first opening and above the second opening, meansfor passing a gaseous medium through a part of said bed extending fromthe end of the container adjacent to the first opening along the greaterpart of the length of the container to fludize that part of the bed, andseparate means for passing a gaseous medium through the remaining partof the bed to fiuidize that part of the bed.

2. An incinerator as claimed in claim l in which the base of thecontainer is apertured and forms one wall of each of a pair of hollowboxes extending end-to-end beneath the base, with one box positionedbeneath that part of the bed which extends along the greater part of thelength of the container and the other box positioned beneath theremaining part of the bed, and separate means associated with each boxfor supplying gaseous medium thereto.

3. An incinerator as claimed in claim l in which said refractorygranular material is alumina.

4. An incinerator as claimed in claim 1 in which means are provided forshredding the town refuse prior to it being introduced into thecontainer through said first opening.

5. An incinerator as claimed in claim l having means supported by thecontainer above the level of the surface of the bed for spraying sewagesludge into the incinerator to be burnt therein.

6. An incinerator as claimed in claim l having means supported by thecontainer above the level of the surface of the bed for introducingoxidizing gas into the container.

7. An incinerator for burning town refuse comprising an elongatecontainer arranged with its longitudinal axis substantially horizontaland having a substantially horizontal apertured base, a first opening inthe container adjacent one end thereof and a second opening in thecontainer wall at the opposite end thereof, said second openingextending to the base of the container,

said base forming one wall of each of a pair of hollow boxes extendingend-to-end beneath the base with one of the boxes extending from the endof the container adjacent said first opening along the greater part ofthe length of the base,

separate means associated with each box for supplying air thereto and abed of alumina in the container extending between said ends with thesurface of the bed positioned below the first opening and above thesecond opening.

8. A method of disposing of refuse which comprises the steps ofproviding first and second masses of refractory granular material in anincinerator defining a first opening positioned above the surface of thefirst mass and a second opening positioned below the surface of thesecond mass, fluidizng the first mass of material by passing a gaseousmedium therethrough, depositing refuse through the first opening intothe incinerator and burning said refuse while supported by saidfiuidized first mass, periodically fiuidizing the second mass ofrefractory granular material by passing a gaseous medium therethrough toallow the noncombustible content of the refuse to pass therethrough andremoving the noncombustible content of said refuse through said secondopening.

1. An incinerator for burning town refuse comprising an elongatecontainer arrangeD with its longitudinal axis substantially horizontal,said container defining a first opening at one end thereof through whichtown refuse is introducible into the container and defining a secondopening at the other end thereof, a bed of granular refractory materialin the container extending between said ends with the surface of the bedpositioned below the first opening and above the second opening, meansfor passing a gaseous medium through a part of said bed extending fromthe end of the container adjacent to the first opening along the greaterpart of the length of the container to fluidize that part of the bed,and separate means for passing a gaseous medium through the remainingpart of the bed to fluidize that part of the bed.
 2. An incinerator asclaimed in claim 1 in which the base of the container is apertured andforms one wall of each of a pair of hollow boxes extending end-to-endbeneath the base, with one box positioned beneath that part of the bedwhich extends along the greater part of the length of the container andthe other box positioned beneath the remaining part of the bed, andseparate means associated with each box for supplying gaseous mediumthereto.
 3. An incinerator as claimed in claim 1 in which saidrefractory granular material is alumina.
 4. An incinerator as claimed inclaim 1 in which means are provided for shredding the town refuse priorto it being introduced into the container through said first opening. 5.An incinerator as claimed in claim 1 having means supported by thecontainer above the level of the surface of the bed for spraying sewagesludge into the incinerator to be burnt therein.
 6. An incinerator asclaimed in claim 1 having means supported by the container above thelevel of the surface of the bed for introducing oxidizing gas into thecontainer.
 7. An incinerator for burning town refuse comprising anelongate container arranged with its longitudinal axis substantiallyhorizontal and having a substantially horizontal apertured base, a firstopening in the container adjacent one end thereof and a second openingin the container wall at the opposite end thereof, said second openingextending to the base of the container, said base forming one wall ofeach of a pair of hollow boxes extending end-to-end beneath the basewith one of the boxes extending from the end of the container adjacentsaid first opening along the greater part of the length of the base,separate means associated with each box for supplying air thereto and abed of alumina in the container extending between said ends with thesurface of the bed positioned below the first opening and above thesecond opening.
 8. A method of disposing of refuse which comprises thesteps of providing first and second masses of refractory granularmaterial in an incinerator defining a first opening positioned above thesurface of the first mass and a second opening positioned below thesurface of the second mass, fluidizing the first mass of material bypassing a gaseous medium therethrough, depositing refuse through thefirst opening into the incinerator and burning said refuse whilesupported by said fluidized first mass, periodically fluidizing thesecond mass of refractory granular material by passing a gaseous mediumtherethrough to allow the noncombustible content of the refuse to passtherethrough and removing the noncombustible content of said refusethrough said second opening.